Wetlands Mitigation in Practice

Mitigation in South Carolina

Commited to maintaining the state's wetland habitats, the South Carolina Department of Transportation is guided by the U.S. Army Corps of Engineers' Mitigation Rule, the 2008 regulations designed, in part, to improve the quality and success of wetland mitigation plans.

The Mitigation Rule emphasizes the strategic selection of compensatory mitigation sites on a watershed basis and established equivalent standards for all three types of compensatory mitigation (mitigation banks, in-lieu fee programs, and permittee-responsible mitigation plans). — USACE Guidelines for Preparing a Compensatory Mitigation Plan

The three types of mitigation are not equal. The Mitigation Rule clearly establishes mitigation banks and in-lieu fee programs — off-site mitigation activities that are not conducted by the permittee — as the preferred routes of mitigating adverse wetlands impacts. These third-party approaches are seen as possessing several advantages:

  • they usually involve larger and more ecologically valuable resources than those being impacted;
  • they can be implemented (and their success evaluated) before the project's wetlands are disturbed;
  • they often involve less effort and cost less to review, implement, and maintain.

SCDOT looks for mitigaton sites within the same watershed. The U.S. Army Corps of Engineers' “Regulatory In-lieu and Bank Information Tracking System” (RIBITS) database is searched to determine if the project is located within the service area of any already approved stream mitigation banks or in-lieu fee programs. Local mitigation bank sponsors may also be contacted about opportunities to acquire the needed stream credits.

But the number of approved mitigation banks and in-lieu fee programs in South Carolina is limited and, if a proposed project is not located within the service area of one, the applicant will be required to develop and implement a permittee-responsible mitigation (PRM) plan detailing how impacts will be offset. Two cases illustrate how PRM mitigation played out in South Carolina.

King's Branch mitigation proposal
The King's Branch site: an on-site mitigation plan
Lynches River site mitigation plan
Lynches River site mitigation plan: mitigating off-site

Mitigation can be pursued on-site in some cases. The King's Branch mitigation site in Berkeley County, South Carolina, illustrates this scenario. The mitigation site is immediately adjacent to the roadway improvement that necessitated the mitigation.

In other cases, the possibiity of on-site mitigation does not exist or might not be the best option available. The Lynches River site in Darlington County, South Carolina, is such a site. The mitigation credits it provided were used to offset five road projects in Florence.